Sleeve-valve internal-combustion engine



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y Filed-mnu. 1926 3 sheets-sheet 1 @EL 4 p ther A. El aw Nov.f22, 1927. 1,650,120

L .'A. GAw

SLEEVE VALVE INTERNAL COMBUSTION ENGINE Filed Aug. 11. 1926 s sneets-sneet 2` .Bchel-1A. El aw L. A. GAW

' 'SLEEVE VALVE INTERNAL COMBUSTION ENGINE Nav, 2z, 1927.

Filed Aug. 11. 1925 s sheets-sheet 5^ V u f l ll|ln l HI `T 7 1 L;

LLLU'LEF A EELW 1n/vento Patented Nov. 22, 1927.

UNITED STATES PATENT OFF-ICE.

LUTHER A. GAW, OF CHARLOTTESVILLE, -VIRGINIA, ASSIGNOR TO DILLON-GA'W MOTOR COMPANY, 0F FAYETTEVILLE, WEST VIRGINIA, A CORPORATION OF WEST VIRGINIA.

SLEEVE-VALVE INTIEIRNAIi-COMBUS'IIONv IliliIGII'E.y

Application led August 11, 1926. Serial Noi. 128,651.

This invention relates to improvements in the sleeve valve type of interna-l combustion engine.

The primary object of this invention is the provision `of an improved cylinder casing block and head construction. for most efficiently regulating the intake and exhaust of fuel and gas.

A further object of this invention is the provision of an improved cani construction for operating sleeve valves.

A further object of this invention is the provision of improvements in sleeve `valve operating mechanisms such as generically set forth in my United lStates Patent #1,286,275, issued December 3, 1918, and my cti-pending application, Serial *.No. 61,722, filed October 10, 1925; the.l present application embodying iinproven'ients thereover in the simplification of the sleevev valve4 y .;Figure 13 showing the` positions of the cams 'asft'he exhaust portis l]ust starting to open.

operating mechanism. I

Other object-s and of the following detailed description. Y

In the accompanying drawings, forming a 'part of this specification, and wherein similar reference characters designate corresponding parts throughouttlie several views,

Figure 1 is a longitudinal sectional view taken thru a cylinder of the improved internal combustion engine. showing the sleeve valve, its operating mechanism, and the piston construction in the position which they will assume with respect to the intake and exhaust ports at the start of the power Stroke.

Figure 2 is a sectional View of the details illustrated in Figure 1, but showing the parts arranged as they will appear as the ex'- haust is taking place.

Figure 3 is an enlarged sectional view of the upper portion of an engine -cylinder, showing the sleeve valve in position when the exhaust is fully open. n

Figure 4 is a sectional view of details taken at right angles to the View illustrated in Figure 3, substantially on the line 4-1 of Figure 3.

Figure 5 is a sectional View taken substantially on the line 5-5 of Figure 4.

advantages of this in'-2 veution will be apparent during tliefcoursef jshowing the cylinder intake Aport with the adjacent 'intake-port of the sleeve-valve just ,Figure 6 is a sectional view taken substantiallxyr on the line 6-6 of Figure 2.

Figure l is a fragmentary view, partly in section, showing means uponvwliich the cams directly engage for causing an operative movement of the sleeve valve'. v

Figures 8 and 9 are sectional views taken y substantially on their respective lines in Figure 1 of the drawings.

Figures 10 to 13 inclusive are views, partly diagrammatic, illustrating various positions of the cams during operation upon the means which operates the sleeve valve; Figure 10 showing vthe cams as they appear at the start of the opening of the intake port;

Figure 11 showing the positions of the cams as they appear as the intake about the starting to close and compression is about to start; Figure 12 showing the position of the cams at the startv of the "power stroke; and

Aliligruiga14 is a. fragmentary sectional view starting to open.

In the drawings, wherein for the purpose of illustration is shown only a preferred embodiment of the improved sleeve valve internal combustion engine, the letter-A may generally designate the -engine, which may include the cylinder block or casing construction B which includes a crank case C wherein a crank shaft D is rotatably'niounted. A piston E operatesv in each of the cylinders of the engine, connected by a rod F to the crank shaft D in the usual manner. A sleeve valve G operates in each cylinder between the piston and the 1cylinder walls, and the sleeve G is controlled by cam means H operating on meansL which is connected with the sleeve valve. A detachable cylinder head construction M is provided for each cylinder of the engine A, and preferably only a single novel water hood or inanifold P is provided for cooperation upon the cylinder block B and with the cylinder heads M to regulate the flow of the cooling medium. v

The cylinder block B is preferably pro# vided with any approved number of cylinder chambers 15, each of which open directly on the top surface of, the cylinder block B and on the upper openings o f the cylinder chambers 15 detachable ind1v1dual cylinder heads M are adapted to be positioned in a novel relation to be subsequently described. The cylinder block B is of course provided with a water jacket providing water compartments 17 surrounding each cylinder, and these water compartments have outlets 19 directly' on the top surface of the cylinder block, so that the water may circulate about the cylinders thru the openings 19 into the water hood or manifoldi l) and about the individual detachable cylinder heads M for cooling the latter, in the relation of parts to be more fully detailed hereinafter.

F or each cylinder chamber l the block B is provided with an upper transverse intake port 2:?, and an opposite but preferably lower exhaust port 23; these ports being preferablyf tapered in a converging relation towards and into their respective, cylinder chambervs'l wherein the sleeve valves (l are slidable. Suitable oil ducts 24 may be provided inl the block B for oiling the piston and sleeve action, in any approved relation.

The cylinder block B is of course mounted on the crank case C in any approved and conventional relation, and the crank shaft C is conventionally tons E. L

The sleeve valves G are provided in each of the cylinder` fchambers in snug sliding relation therein and each of these sleeveA valves G includes an upper transverse ,-intake port 26 and an opposite but preferably lower exhaust yport 27 adapted to cooperate respectively with the port-s 22 and 23 of the engine block. -ZThe ports 26 and 27 may be of nany lengthl circumferentially about the sleeve desired,1 in order to render the intake and exhaustl--most efficient. These ports, however, are" horizontally elongated as illustrated in', Figure 4 of the drawings.

Referring to the novel means H and L for slidable operation of the sleeve valves G, the principle of operation is substantially the same as set forth in my above mentioned co-pending" application, but the operating details are' different and considered an improvement.

The cam means H includes a cam shaft 30 longitudinally bearing in the crank case C, in any approved manner, and connected by means 31 with the crank shaft D for operation at one-half cr'ank shaft speed and pref- -erably rotatable in the same direction. For each sleeve valve the cam shaft 30 is provided with main and auxiliary cams 32 and 33 respectively, which respectively have throw ortlons 34 and 35, arranged in a relation o 90 about the cam shaft. The deconnected to the pis-v sign of these Cams is important as insuring an elicient operation of the sleeve valve for intake and exhaust action. rl`he main cani is so designed that from the throw portion 34 in the direction of rotation of the cani shaft, the same abruptly slopes with a prefably flat side in direction toward the axis of the cam shaft 30, and from thence gradually increases on an arc, the radiusl of which gradually increases from the axis ot the cani shaft 30 until the throw portion 34 is reached. In contrzulistinction to this the auxiliary cani 33 from its throw portion 255 gradually slopes on an arc at' a gradually decreasing radins from the throw portion 35 in a direction ot' rotation ot' the cani` and at the approach to the throw portion 35 in the direction of rotation of the czun the anxiliary cani has preferably a tlat lside and slopes abruptly into the throw portion. The reason for so designing the pair of cams for each sleeve valve is that the distance from one point of one caxn to a diainetrieally opposed point on the other cani should be the same, at any point from which such measurementis taken, and which feature is set forth in my co-pending application above referred to, and is fully explained therein.

Referring to the means'L which the cams operate to canse an operation ofthe sleeve valves G, the saine is somewhat of a departure from the construction of my co-pending application above referredto, and includes a crescent shaped frame 38 having a hub portion 39 intermediate its ends provided with a passageway 40 therethrough transverse to the plane of the crescent shaped frame 38, and-which passageway is adapted to detachably. receive a pin 4lwhich is supported by spaced bracket arms 42 and 43 integral or rigid with a detachable bracket wall 44 which is formed as part of the crank case C at a side thereof. The crescent shaped frame 38 is thus pivotally Supported by the pin 41 in a vertical plane and below the pivot connection of the frame 38 the same provides a forwardly extending haltl circled supportiilig arm 45 and above the same is provided a quarter circled arm 46 rigid with the arm 45, although reduced in thickness with respect thereto, the arm 46 being only of one half the thickness of the arm 45, for a purpose which will be subsequently described. The free ends of the arm portions 45 and 46 are spaced at 48, to permit the assemblage of the frame 38 .with the cam shaft 30 extending centrally thru the passageway between the arms 45 and 46, as is illustrated in the drawings.

At its free end the lower and longer arm portion 45 is provided with a slot or recess 49 which radially opens outwardly and is adapted to slidably bear on the intermediate portion of a pin 50 which is supported at its ends by spaced brackets 51; the brackets 51 being secured on the lower end of the sleeve valve G below the cylinder block.

As the cams actupon the frame 3-8 it is readily obvious thatI the same is rocked on itsl pivot pin l1 and due to the loose connection with the pin 5t), the sleeve valve G will be reciprocated .within its cylinder compartment to cause the proper operation thereof. Referring now to the specific parts of the frame 38 with which the main and auxiliary cams 32 and 32% cooperate, the lower or longer arm midway between the ends thereof is provided with a detachable supporting boltI or member 52. transversely extending beyond the outer side of the frame arm 45, where the saine rotatably supports an antifriction roller 53. which includes inner and outer races willi ball bearings therebetween, the, outer race of the anti-friction roller 53 being adapted to be engaged atits outer circum't'erence by the periphery of the auxillary cam 323 during rotation of the latter.

Atits free end the reduced shorter arm -l6 is provided with a detachable bolt or pin 55, which extends laterally from the reduced side of the shorter segment-al arm 46; the said pin or bolt 55 being adapted to pivotally support the one end of a preferably straight arm 57 which extends from the pivot member in a direction away from the cylinder sleeve valve G. This construction best illustrated in Figure 7 of the drawings. A. vertical pin 60 is rigidly supported b v the arm 46 adjacent the free end of the movable arm 57, and the movable arm 5T is provided with an aperture 61 therein thru which the pin 60 loosely extends. At its free end the pin 6() is screw vthreaded for adjustably receiving a retaining nut 62, and upon the pin 60 is a spring 63 under compres: -;ion` engaging the nut 62 at one end and the free end of the arm 5T at the opposite end. lo .normally force the free end of the arm 6l towards the pivot Apin 11 of the frame 238. Intermediate its ends and preferably closer to the pivot pin 55, the arm 57 is provided with a detachable pin or bolt 65. on which an anti-friction roller 66 is detachably supported, which consists of inner and outer faces with ball bearings therebetween. the outer race being adapted to be engaged by the outer periphery of the main cam 32 during rotation of the latter.

lt is to be noted that the anti-friction rollers 53 and 66 are located at opposite sides of the frame V38, and that they are at diai'netrically opposed locations with respect to the cam shaft 30, so that the one roller engages the auxiliary cam and the other roller engages the respective main cam; this construction being provided in connection with each sleeve valve oprating mechanism. The crank case C is altered slightly in construction beyond the conventional formation to receive details of the means L, and as above mentioned the bracketplate 44 is detachably connected, as at 68, to the body portion 69 of the crank case in order to pivotally support the frame 38. In the top wall of the crank case C laterally of each cylinder block, is provided a top opening 70 in the crank case top wall thru which the upper ends of the. frames 38 extend, and detachable caps 71 are secured in any approved manner over these openings 70, to permit of facile access to `details of the operating means L.

As before mentioned a cylinder head M is provided in connection with each cylinder of the engine A. Each cylinder head com prises an outer substantially cylindrical shaped shell 80, 'which is insertable downwardly into the upper end of the cylinder chamber 15, so that the outer circumference thereof is spaced from the inner surface of Y the walls of the cylinder chamber 15, to provide an annular compartment 8l which extends longitudinally along the upper portion of the cylinder chamber 15, and into which the upper end of the sleevevalve extends. The upper margins of the other shell are provided with laterally extending attaching flanges 82, secured over the top surface ofthe cylinder block B and provided with openings 83 therethrough for receiving attaching bolts 8l by means of which to secure the respective cylinder heads in place on the cylinder block B, as is well illustrated in Figure 5 of the drawings. These flanges 82 are provided with transverse apertures 86 therethrough aligning with the openings 19 thru the top wall of the cylinder block B, and thru which water passes into the compartment 90 of the water receiving hood P.

An inner shell 91 is also provided as part of each cylinder head M, which is of tubular formation and extends centrally upward thru the passageway 92 provided thru the outer shell 80. This inner shell 91 'is integral at its lower end with the lower end of the outer shell 80, and from this connection, illustrated at 94 in Figure 1 of the drawings, the inner shell 91 extends upwardly in spaced relation with the inner walls of the outer shell toiprovide an annular space 95 open at the top of the compartment 90 of the water hood P, so that water may enter and circulate about the space 95 to cool the upper portion of the sleeve valve and reciprocating parts of the sleeve valve operating mechanism, as well as to generally cool the entire upper part of the cylinder in a novel relation.

The inner shell 91 is provided with a downwardly facing frusto-conical compartment 98, which is of greatest diameter at its outlet into the chamber within the Sleeve valve Gr and tapers in a converging relation an intake port 105y transversal cylindciheadj'M, which aligns directly with vtherefrom upwardly to a spark plug-supporting wall 99 which is integrally provided the tapered vcompartment 98 of the cylinder ,j A "transverse web portion connects the inner and outer shells 91 and 80. to provide thru the the intake, port 22 of the cylinder block B for the respective cylinder in which the cylinder head M is assembled, so that the inlowing fuel charge4 passes thru the ports 22 and into the upper or smaller end of the tapered compartment 98. It is to be noted that the intake port 105 is relatively long transversely about, the cylinder head M and the intake port 105 tapers in a constricted relation towards the center of the compartment 98, as is illustrated by the tapered Sides in Figure 6 of the drawings. Also, the web portion Connecting the inner and outer shells is downwardly sloped from the bottom of the intake port 105 to provide a downwardly sloping surface 112 from the outer edge of the intake port 105 to the interseof tion of the surface 112 with the upwardly tapered surface .which defines the tapered compartment 98, as is well illustrated in Figures 1, 2 and 14 of the drawings. It is to be not-ed that the intake port 105 is fiush with the lower surface of the wall 99 so that the inflowing charge will pass direct.- ly onto the electrodes of the spark plug 101, and be whirled about in a turbulent flow .within the tapered compartment 98, due to the manner in which the same enters lthe compartment 98, and due to the shape Aof said compartment 98.

The outer lshell 80 at a location above the intake port 105 is provided with an annular groove 114 wherein a preferably expansible packing ring 115y is received, which engages in a sealed yconnection with inner wall of the slidingsleeve valve G, to seal against leak of compression above the intake port` 105. Below the intake port 105 the outer shell 80 isalso provided with an annular groove 117., wherein an expansible packing or piston ring 118 is adapted to be received, in a sealed engagement with the inner wall of the sleeve valve G, below the intake port 105. This piston-ring 118 is formed as best illustrated in Figure 14, with reduced flanges A 119 at the top and bottom margins thereof, which engage the exterior surfaces of the outer shell 8O above and below' the groove 117, in order vto* best anchor the packing ring in `position to provide the most efficient I -valve G, which the piston ring 118 is adapt ed to seal at different locations in the 4sliding movement of the sleeve valve.

rl`he inner tubular shell 91 extends at its upper end above the top surfaces of the top wall of the cylinder block B and above the top surface of the flanges 82 of the cylinder heads M. Adjacent to the plane of the top surface of the flanges 82, each cylinder head M on the inner shell 91 thereof is rprovided with an annular hood supporting flange 120 which provides an upwardly facing shoulder. The upper end of the shell 91 above the flange 120 is externally screw threaded for detachably receiving a hood clamping nut 122.

The water hood P extends the length of the engine A, and the same is provided with side walls 125, which extend' along opposite sides of the engine. It is furthermore provided with a top wall 126, and for each cylinder head M 'the hood top wall 126 is provided with a depending tubular extension 128 which extends downwardl into the compartment y90 of the hood, for fif'eely receiving the upper end of the inner shell 91 of the respective cylinder heads M; the lower edges of each of the tubular portions 128 resting on the supporting flange 120 of the respective cylinder head with which it cooperates, in order to properly support the hood P in position against eccentric clamping action. In this position the lower flanged ends of the side walls rest on the top surface of the top wall of the cylinder block B, and packing 130 is preferably provided l: Itween the abutting edges at the bottoms of the side walls 125'and the top wall of the cylinder block B, to provide a liquid seal. In this position the top screw threaded ends of the inner shells 91 extend above the top surface of the top wall 126, for receiving the nuts 122 which are then clamped against the top wall of the hood, to hold the latter in place. Washer arrangements are. provided at the location where the tubular 'shells 91 leave the hood, which the nuts 122 force into engagement with the top wall of the hood about each inner shell 91 to seal the juncture and prevent leakage. The hood D may be provided with any suitable connection 140, illustrated'in Figure 3, which may be connected with the water cooling radiator (not shown).

From the foregoing description of this invention it is believed that the operation of the engine will be apparent. In Figure 10 is illustrated the position of the cam for the start of the intake of fuel to the cylinder chamber for this operating mechanism. It

will be noted that the throw of the main cam 32 is just about to lift the roller 66 on which it operates to the highest extent, and ot' course this will roi-lc the trame 38 on its pivot piu 4l and litt the sleeve valve G. The position ot' the sleeve valve and particularly its intake port 2G tor this arrangement of the cani (Figure 10) is illustrated in Figure 14.-, and it is to be noted that the intake port 2G is just about to come into alignment with the aligning ports 22 and 105, and at which instance the suction, duc to the downward traveling piston, will cause an intake of the fuel charge into the cylinders of the engine. The ,lucl charge, due to the compartment 98 in which the same first enters, will first pass in a turbulent flow directly across the electrodes of the spark plug, and most eiiciently enter the cylinder chamber within the sleeve valve G, as is readily' apparent.

rIhe position of the cams illustrated in Figure 11 shows the relation which they assume when the intake is just starting to close and the main throw portion of the main cam 32 has moved beyond the roller 66 on which it operates, and the throw of the cam 32 is decreasing with respect to the roller 66, whereas the auxiliary cam 33 is operating with a gradually increasing radius on its roller 53, which action lowers the sleeve valve G to bring the port 26 downwardly past the aligning ports 22 and 105. Ther cams move from their position illustrated in Figure 11 to their position illustrated in Figure 12, and during which movement the compression stroke of the piston is taking effect. The view illustrated in Figure 12 shows the positions which the cams assume when the throw of the crank shaft is at top center, and the start of the power stroke is Jtaking place. During this position the intake and exhaust ports of the sleeve valve are closed to alignment with the housing intake and exhaust ports, as is quite apparent, and during the power stroke the cams move from the position illustrated in Figure 12 to the position illustrated in Figure 13.

In Figure 13 the cams show the position which they assume at the start of the eX- haust stroke, and the relation of the exhaust port ot' the sleeve valve G for this position of the cams is illustrated in Figure 2 of the drawings, for it showsl the sleeve valve G lowered to start to align the exhaust port 27 with the exhaust port 23 of the engine block B to permit the escape of exhaust gases.

In so far as the individual cylinder head construction for each cylinder is concerned, it is apparent that the same not only admits of better access to the working parts of the engine, but due to the novel arrangement thereof, the fuel charges inlet so as to maintain the spark plug electrodes clean. The most important feature in the novel construction of the individual cylinder head, is in the fact that by projecting into the upper portion of the cylinder the same provides an annular compartment which slidably receives the upper end of the sleeve valve in such a piston ring sealed' relation at opposite sides ot' the intake port of the housing that the engine is especially desirable for use where high compression is desired. Thus, the engine will operate with increased efficiency with good fuel, and will effectively operate under circumstances where low grade fuels are used, due to the absence of loss of compression.

Various changes in the shape, size, and arrangement of parts may be made to the forms of invention herein shown and described, without departing from the spirit of the inventions or the scope of the claims.

I claim:

1. In an internal combustion engine the combination of a cylinder having port means therein, a sleeve valve slidable in the cylinder having port means therein adapted .to cooperate with the cylinder port means, plston means .,lidable in the sleeve valve, a segmentalpivotally connected frame having a pivotal slidable connection with the sleeve valve, cam shafts, and cam means on the cam shafts for operating on said pivoted frame to cause a reciprocatory movement of said sleeve valve.

2. In an internal combustion engine the combination of a cylinder having port means therein, a sleeve valve slidable in the cylinder having port means therein adapted for cooperation with the cylinder port means,

Apiston means slidable in the sleeve valve, a

crescent shaped frame pivoted intermediate its ends, means providing a slidable pivot connection of the crescent shaped frame at one end with said sleeve valve, a cam shaft extending thru the hollow of the crescent shaped frame, a pair of cams on said cam shaft having the throws thereof relatively offset circumferentially about the cam shaft, and anti-friction rollers carried by the crescent shaped frame at diametricallv opposed locations on the crescent shaped frame, one of said anti-friction rollers having engagement with one of the cams and other roller having engagement with the other cam.

3. In an internal combustion engine the combination of a cylinder having port means therein, a sleeve valve slidahle in the cylinder having port means therein adapted for cooperation with the cylinder port means, piston means slidable in the sleeve valve, a. crescent shaped frame pivoted intermediate its ends, means providing a slidable pivot connection of the crescent shaped frame at one end with said sleeve valve, a cam shaft extending thru the hollow of the crescent shaped frame, a pair of cams on said cam shaft having the throws thereof relatively n frequency output of the reproducer.

By com arison of Figs. 3 and 4 it will be seen that ig. 4 de arts from the ideal case in having art of t e shunt elasticity in series with t e conductance and part in shunt instead of all in shunt, as showny in Fig. 3. Since Equation 5 above holds only when all of the elasticity is in shunt to the conductance, the ratio of the elasticity 77 to the elasticity 79 should be made as large as possible and therefore insure that the network more nearly approximates the condition covered by Equation 5.-

Electrical networks such as that shown in Fi 1, for example, may be terminated at eac end in a variety of ways, the impedance of the arrangement depending upon the manner ot its termination. Two common terminations are the mid-series type and the mid-shunt type. In the mid-series type, the end series inductances have values equal to one-half of the value of the inductance for a full section and in the mid-shunt termination, the capacity has a value one half the capacity of that of a full section. The mechanical arrangement of Fig. 9 may be made to have a mid-shunt termination, for example,'at the needle en'd by having the elasticity 71 twice the elasticity of the full section, that is, elasticity 71 would have a value twice the elasticity of element 74 or 77, in those cases in which the elasticity 73 may be disregarded. In other cases the elasticity 71 should have a value only approximately one half of that of the elements 77 so as to give the terminating section the same impedance as the other sections. The termination at the carbon chamber end need not be made special, since the impedance of the carbon chamber represents the impedance of an infinite number of sections. A- ready explanation of the manner in which the -network should be terminated is shown in Fig. 2, Where both the series and the shunt elements are split into two parts. The inductance of a full section comprises the sum of elements 81 and 82, while the total capacity for a single section comprises the sum of the capacities 83 and 84. If the network is terminated at the points 86, the inductance 81 is mated with the capacity 85 which isV the same value as either capacity 83 or 84. Inductance 82 is mated with capacity 83. liiductance 87 is mated with capacit 84 and inductance 88 is mated with capacity 89, all of the inductances shown being of equal value and all of the capacities shown being of equal value.

Such a filter can also be terminated at the points 90 and 91, inductance 81 and capacity 85 being omitted, or the network can be terminated at the points 92 and 93, inductances 81 and 82 andcapacities 85 and 83 being omitted. f

It is to be understood that this inventori is not limited to the particular forms that have been described in detail above, since they may be variousl modified Without departing in any wise rom the spirit of the invention as defined in the appended claims.

The invention claimed is:

1. A phonograph reproducer, comprising a carbon button, a flexible closure therefor, a lever arm arranged to be vibrated in accordance with speech frequency vibrations occurring on a sound record, a mechanical transmission line between said lever and said closure comprising a plurality of spaced weights separated by a loose packing of aircushioned material, said carbon chamber being of sufficient depth to avoid a preciable reiiection losses from the wall o said chamber opposite said closure back to said closure. Y

2. An electric device comprising electrodes, conductive granular material packed between said electrodes, means comprising a flexible member contacting with said material for subjecting said material to mechanical vibrations, and means cooperatin with said granular material for causing sai granular material to work into a mechanical impedance on that side of said material opposite said flexible member having an impedance of the same order of magnitude as the impedance of said means which subjects said material to mechanical vibrations.

3. An electric device comprising electrodes, a chamber substantially filled with carbon granular material, means for causin an electric current to flow through sai granular material, and a flexible member included as one side of said chamber, said chamber bein of suiiicient depth that the carbon material adjacent the back wall of said chamber is substantially unaffected by the mechanical vibrations of said flexible member.

4. An electric device comprising a chamber substantially filled with carbon granular material, a flexible member acting as one side of said chamber, means for im ressing mechanical vibrations of signaling re uencies upon said member, means for suppA ying an electric current to a portion of said granular material, the mass of said carbon in said chamber being of suiiicient depth and cross section as to cause the active carbon material to Work into an impedance of the same order ot' magnitude as the impedance of the said means for impressing mechanical vibrations upon said granular material.

Iius

pivoted at the other free end of the frame,`

a cam engaging roller rotatably mounted on said lever eccentrically of the pivot mounting of the lever, and spring means associated with the frame and the level' for urging the latter in a direction to move the last mentioned roller towards the first mentioned roller.

LUTHER A. GAW. 

